A novel NMR-based assay to measure circulating concentrations of branched-chain amino acids: Elevation in subjects with type 2 diabetes mellitus and association with carotid intima media thickness

BCAA mediated microbiota-liver-heart crosstalk regulates diabetic cardiomyopathy via FGF21

BACKGROUND

Diabetic cardiomyopathy (DCM) is one of leading causes of diabetes-associated mortality. The gut microbiota-derived branched-chain amino acids (BCAA) have been reported to play a central role in the onset and progression of DCM, but the potential mechanisms remain elusive.

RESULTS

We found the type 1 diabetes (T1D) mice had higher circulating BCAA levels due to a reduced BCAA degradation ability of the gut microbiota. Excess BCAA decreased hepatic FGF21 production by inhibiting PPARα signaling pathway and thereby resulted in a higher expression level of cardiac LAT1 via transcription factor Zbtb7c. High cardiac LAT1 increased the levels of BCAA in the heart and then caused mitochondrial damage and myocardial apoptosis through mTOR signaling pathway, leading to cardiac fibrosis and dysfunction in T1D mice. Additionally, transplant of faecal microbiota from healthy mice alleviated cardiac dysfunction in T1D mice, but this effect was abolished by FGF21 knockdown.

CONCLUSIONS

Our study sheds light on BCAA-mediated crosstalk among the gut microbiota, liver and heart to promote DCM and FGF21 serves as a key mediator. Video Abstract.

Oral citrate supplementation mitigates age-associated pathological intervertebral disc calcification in LG/J mice

Despite the high prevalence of age-dependent intervertebral disc calcification, there is a glaring lack of treatment options for this debilitating pathology. Here, we investigate the efficacy of long-term oral K3Citrate supplementation in ameliorating disc calcification in LG/J mice, a model of spontaneous age-associated disc calcification. K3Citrate successfully reduced the incidence of disc calcification in LG/J mice without deleterious effects on vertebral bone structure, plasma chemistry, and locomotion. Notably, a positive effect on grip strength was evident in treated mice. Spectroscopic investigation of the persisting calcified nodules indicated K3Citrate did not alter the mineral composition and revealed that reactivation of an endochondral differentiation program in endplates may drive LG/J disc calcification. Importantly, K3Citrate reduced calcification incidence without altering the pathological endplate chondrocyte hypertrophy, suggesting mitigation of disc calcification primarily occurred through Ca2+ chelation, a conclusion supported by chondrogenic differentiation and Seahorse metabolic assays. Overall, this study underscores the therapeutic potential of K3Citrate as a systemic intervention strategy for disc calcification.

Circulating total and H-specific GDF15 levels are elevated in subjects with MASLD but not in hyperlipidemic but otherwise metabolically healthy subjects with obesity

BACKGROUND

Growth differentiation factor 15 (GDF15) is a mitokine, the role of which, total or H-specific, in modulating energy metabolism and homeostasis in obesity-related diseases, such as metabolic dysfunction associated steatotic liver disease (MASLD), has not been fully elucidated in adult humans. We aimed to investigate the fasting and stimulated levels of GDF15, total and H-specific, glucose-dependent insulinotropic polypeptide (GIP) and C-peptide, in two physiology interventional studies: one focusing on obesity, and the other on MASLD.

METHODS

Study 1 investigated individuals with normal weight or with obesity, undergoing a 3-h mixed meal test (MMT); and study 2, examined adults with MASLD and controls undergoing a 120-min oral glucose tolerance test (OGTT). Exploratory correlations of total and H-specific GDF15 with clinical, hormonal and metabolomic/lipidomic parameters were also performed.

RESULTS

In study 1, 15 individuals were included per weight group. Fasting and postprandial total and H-specific GDF15 were similar between groups, whereas GIP was markedly higher in leaner individuals and was upregulated following a MMT. Baseline and postprandial C-peptide were markedly elevated in people with obesity compared with lean subjects. GIP was higher in leaner individuals and was upregulated after a MMT, while C-peptide and its overall AUC after a MMT was markedly elevated in people with obesity compared with lean subjects. In study 2, 27 individuals were evaluated. Fasting total GDF15 was similar, but postprandial total GDF15 levels were significantly higher in MASLD patients compared to controls. GIP and C-peptide remained unaffected. The postprandial course of GDF15 was clustered among those of triglycerides and molecules of the alanine cycle, was robustly elevated under MASLD, and constituted the most notable differentiating molecule between healthy and MASLD status. We also present robust positive correlations of the incremental area under the curve of total and H-specific GDF15 with a plethora of lipid subspecies, which remained significant after adjusting for confounders.

CONCLUSION

Serum GDF15 levels do not differ in relation to weight status in hyperlipidemic but otherwise metabolically healthy individuals. In contrast, GDF15 levels are significantly increased in MASLD patients at baseline and they remain significantly higher compared to healthy participants during OGTT, pointing to a role for GDF15 as a mitokine with important roles in the pathophysiology and possibly therapeutics of MASLD. Trial registration ClinicalTrials.gov NCT03986684, NCT04430946.

Association between branched-chain amino acids and renal function in the ELSA-Brasil study

BACKGROUND & AIMS

Epidemiologic studies show high circulating Branched-chain amino acids (BCAA) are associated with excess body weight, impaired fasting glucose, insulin resistance, high blood pressure, and dyslipidemia. There is scarce data on the association between renal function and circulating levels of BCAA. Therefore, we aim to study this association in a sample of the Brazilian Longitudinal Study of Adults (ELSA-Brasil) METHODS: We analyzed participants who had at the baseline BCAA: valine, isoleucine, and leucine measured through nuclear magnetic resonance. The outcomes evaluated were estimated glomerular function (eGFR - CKD-EPI without race) and 12h-albumin-creatinine ratio (ACR). In addition, we built unadjusted and adjusted multivariable linear regression models to investigate the association between the BCAA (total and individual) and eGFR and ACR.

RESULTS

We studied 4912 participants (age 51.7(±9.0) years, 53.4% women, 59.5% White (59.5%), 32.7% hypertension, and 18.2% diabetes). The mean BCAA level was 429.15 ± 87.15. The mean eGFR was 84.95 ± 15 ml/min/1.73 m2, and the median ACR was 6.5 (1.8-4920) mg/g. Descriptive analyses comparing eGFR stratified <60 ml/min/1.73 m2 and ACR≥30 mg/g demonstrate that BCAA levels are higher in patients with eGFR<60 and ACR ≥30. Regarding eGFR, an inverse association was detected with BCAA levels when adjusted for demographic variables, and it is not maintained after adjustments for other confounders. Also, a positive association was found for ACR≥30 mg/g, and BCAA levels, and this association is not confirmed after adjustments.

CONCLUSIONS

BCAA levels were inversely associated with eGFR and positively associated with ACR. Further studies are necessary to allow the comprehension of those associations.

Mediterranean Diet Adherence and Risk of All-Cause Mortality in Women

Importance

Higher adherence to the Mediterranean diet has been associated with reduced risk of all-cause mortality, but data on underlying molecular mechanisms over long follow-up are limited.

Objectives

To investigate Mediterranean diet adherence and risk of all-cause mortality and to examine the relative contribution of cardiometabolic factors to this risk reduction.

Design, Setting, and Participants

This cohort study included initially healthy women from the Women's Health Study, who had provided blood samples, biomarker measurements, and dietary information. Baseline data included self-reported demographics and a validated food-frequency questionnaire. The data collection period was from April 1993 to January 1996, and data analysis took place from June 2018 to November 2023.

Exposures

Mediterranean diet score (range, 0-9) was computed based on 9 dietary components.

Main Outcome and Measures

Thirty-three blood biomarkers, including traditional and novel lipid, lipoprotein, apolipoprotein, inflammation, insulin resistance, and metabolism measurements, were evaluated at baseline using standard assays and nuclear magnetic resonance spectroscopy. Mortality and cause of death were determined from medical and death records. Cox proportional hazards regression was used to calculate hazard ratios (HRs) for Mediterranean diet adherence and mortality risk, and mediation analyses were used to calculate the mediated effect of different biomarkers in understanding this association.

Results

Among 25 315 participants, the mean (SD) baseline age was 54.6 (7.1) years, with 329 (1.3%) Asian women, 406 (1.6%) Black women, 240 (0.9%) Hispanic women, 24 036 (94.9%) White women, and 95 (0.4%) women with other race and ethnicity; the median (IQR) Mediterranean diet adherence score was 4.0 (3.0-5.0). Over a mean (SD) of 24.7 (4.8) years of follow-up, 3879 deaths occurred. Compared with low Mediterranean diet adherence (score 0-3), adjusted risk reductions were observed for middle (score 4-5) and upper (score 6-9) groups, with HRs of 0.84 (95% CI, 0.78-0.90) and 0.77 (95% CI, 0.70-0.84), respectively (P for trend < .001). Further adjusting for lifestyle factors attenuated the risk reductions, but they remained statistically significant (middle adherence group: HR, 0.92 [95% CI, 0.85-0.99]; upper adherence group: HR, 0.89 [95% CI, 0.82-0.98]; P for trend = .001). Of the biomarkers examined, small molecule metabolites and inflammatory biomarkers contributed most to the lower mortality risk (explaining 14.8% and 13.0%, respectively, of the association), followed by triglyceride-rich lipoproteins (10.2%), body mass index (10.2%), and insulin resistance (7.4%). Other pathways, including branched-chain amino acids, high-density lipoproteins, low-density lipoproteins, glycemic measures, and hypertension, had smaller contributions (<3%).

Conclusions and Relevance

In this cohort study, higher adherence to the Mediterranean diet was associated with 23% lower risk of all-cause mortality. This inverse association was partially explained by multiple cardiometabolic factors.

Triglyceride/HDL cholesterol ratio and lipoprotein insulin resistance Score: Associations with subclinical atherosclerosis and incident cardiovascular disease

BACKGROUND

The triglyceride/HDL cholesterol (TG/HDL-C) ratio and the Lipoprotein Insulin Resistance (LP-IR) score are lipid markers of insulin resistance. Their associations with carotid intima media thickness (cIMT; subclinical atherosclerosis) and incident cardiovascular disease (CVD) have not been thoroughly investigated.

METHODS

In a cross-sectional cohort (89 subjects without type 2 diabetes (T2D) and 81 subjects with T2D we determined cIMT (ultrasound), homeostasis model assessment of insulin resistance (HOMA-IR) and the TG/HDL-C ratio. The LP-IR score, based on 6 lipoprotein characteristics determined by nuclear magnetic resonance spectroscopy, was measured in 123 participants. A prospective study was carried out among 6232 participants (Prevention of REnal and Vascular ENd-stage Disease study).

RESULTS

Cross-sectionally, the adjusted associations of HOMA-IR, the TG/HDL-C ratio and the LP-IR score with cIMT were approximately similar (standardized β = 0.34 (95 % CI 0.19-0.48), 0.24 (95 % CI 0.09-039) and 0.41 (95 % CI 0.23--0.59), respectively). Prospectively, 507 new cases of CVD were observed after a median follow-up of 8.2 (interquartile range 7.5-8.8) years. HOMA-IR, the TG/HDL-C ratio and LP-IR were each associated with incident CVD independent of potential confounders (HR 1.12, 95 % CI 1.02-1.24;1.22, 95 % CI 1.11-1.35 and 1.15. 95 % CI 1.01-1.31, respectively). The association of the TG/HDL-C ratio with incident CVD was somewhat stronger than that of HOMA-IR.

CONCLUSION

Lipoprotein-based markers of insulin resistance are at least as strongly associated with subclinical atherosclerosis and clinical atherosclerosis development as HOMA-IR, obviating the need to measure insulin to determine the impact of insulin resistance. For practical purposes, the easily obtainable TG/HDL-C ratio may suffice.

Adherence to the Mediterranean diet and nuclear magnetic resonance spectroscopy biomarkers in older individuals at high cardiovascular disease risk: cross-sectional and longitudinal analyses

BACKGROUND

The Mediterranean diet (MedDiet) has been related to a decreased risk of cardiovascular disease (CVD) and diabetes.

OBJECTIVES

We aimed to prospectively assess the relationship between adherence to the MedDiet and advanced lipoprotein subclass profiles and glucose metabolism and inflammation markers, as determined by nuclear magnetic resonance (NMR) spectroscopy.

DESIGN

We conducted cross-sectional and longitudinal analyses within the framework of the PREvención con DIeta MEDiterránea study in 196 participants from the Reus-Tarragona center. Adherence to the MedDiet was assessed using a 14-item validated questionnaire [Mediterranean Diet Adherence Score (MEDAS)]. Plasma lipoprotein subclasses and molecular metabolite profiles were determined using NMR spectra collected on a Vantera Clinical Analyzer at baseline and after 1 y of follow-up. Baseline and 1-y categories of MEDAS were related to measures of lipoprotein atherogenicity and diabetes risk using multivariable-adjusted analysis of covariance models.

RESULTS

Compared with participants in the lowest category of baseline MEDAS, those in the highest category showed higher concentrations of total high-density lipoprotein (HDL) particles and H1P HDL, lower concentrations of very low-density lipoprotein (VLDL)-triglyceride, smaller size of VLDL, and lower concentrations of very large VLDL, as well as lower concentrations of branched-chain amino acids, leucine, and GlycA and reduced Diabetes Risk Index (DRI) scores. In addition, participants who increased by 3 or more points in their 1-y MEDAS showed an increase in concentrations of H7P-HDL, H5P-HDL, and citrate, and reduced acetone and DRI scores compared with those with lesser adherence increases.

CONCLUSIONS

In older adults at high cardiometabolic risk, higher MEDAS was associated with modest beneficial changes in lipoprotein and glucose metabolism. The results suggest that lipoprotein subclass distribution and glycemic control are potential mechanisms behind the well-known salutary effects of MedDiet on CVD and diabetes risk. Future clinical trials exploring the effects of the MedDiet on advanced lipoprotein subclass profiles and glucose metabolism markers are needed to confirm the results of our study.

TRIAL REGISTRATION NUMBER

This trial was registered at controlled-trials.com as ISRCTN35739639.

Plasma Levels of Branched Chain Amino Acids, Incident Hip Fractures, and Bone Mineral Density of the Hip and Spine

OBJECTIVE

Branched chain amino acids (BCAA) are building blocks for protein, an essential component of bone. However, the association of plasma levels of BCAA with fractures in populations outside of Hong Kong or with hip fractures in particular is not known. The purpose of these analyses was to determine the relationship of BCAA including valine, leucine, and isoleucine and total BCAA (SD of the sum of Z-scores for each BCAA) with incident hip fractures and bone mineral density (BMD) of the hip and lumbar spine in older African American and Caucasian men and women in the Cardiovascular Health Study.

DESIGN

Longitudinal analyses of association of plasma levels of BCAA with incident hip fractures and cross-sectional BMD of the hip and lumbar spine from the Cardiovascular Health Study.

SETTING

Community.

PARTICIPANTS

A total of 1850 men (38% of cohort) and women; mean age 73 years.

MAIN OUTCOME MEASURES

Incident hip fractures and cross-sectional BMD of the total hip, femoral neck, and lumbar spine.

RESULTS

In fully adjusted models, over 12 years of follow-up, we observed no significant association between incident hip fracture and plasma values of valine, leucine, isoleucine, or total BCAA per 1 SD higher of each BCAA. Plasma values of leucine but not valine, isoleucine, or total BCAA, were positively and significantly associated with BMD of the total hip (P = .03) and femoral neck (P = .02), but not the lumbar spine (P = .07).

CONCLUSIONS

Plasma levels of the BCAA leucine may be associated with higher BMD in older men and women. However, given the lack of significant association with hip fracture risk, further information is needed to determine whether BCAAs would be novel targets for osteoporosis therapies.

The Mediterranean Diet, Cardiometabolic Biomarkers, and Risk of All-Cause Mortality: A 25-Year Follow-Up Study of the Women's Health Study

Background

Higher consumption of Mediterranean diet (MED) intake has been associated with reduced risk of all-cause mortality but limited data are available examining long-term outcomes in women or the underlying molecular mechanisms of this inverse association in human populations. We aimed to investigate the association of MED intake with long-term risk of all-cause mortality in women and to better characterize the relative contribution of traditional and novel cardiometabolic factors to the MED-related risk reduction in morality.

Methods

In a prospective cohort study of 25,315 initially healthy women from the Women's Health Study, we assessed dietary MED intake using a validated semiquantitative food frequency questionnaire according to the usual 9-category measure of MED adherence. Baseline levels of more than thirty cardiometabolic biomarkers were measured using standard assays and targeted nuclear magnetic resonance spectroscopy, including lipids, lipoproteins, apolipoproteins, inflammation, glucose metabolism and insulin resistance, branched-chain amino acids, small metabolites, and clinical factors. Mortality and cause of death was ascertained prospectively through medical and death records.

Results

During a mean follow-up of 25 years, 3,879 deaths were ascertained. Compared to the reference group of low MED intake (0-3, approximately the bottom tertile), and adjusting for age, treatment, and energy intake, risk reductions were observed for the middle and upper MED groups with respective HRs of 0.84 (95% CI 0.78-0.90) and 0.77 (95% CI 0.70-0.84), p for trend <0.0001. Further adjusting for smoking, physical activity, alcohol intake and menopausal factors attenuated the risk reductions which remained significant with respective HRs of 0.92 (95% CI 0.85-0.99) and 0.89 (95% CI 0.82-0.98), p for trend 0.0011. Risk reductions were generally similar for CVD and non-CVD mortality. Small molecule metabolites (e.g., alanine and homocysteine) and inflammation made the largest contributions to lower mortality risk (accounting for 14.8% and 13.0% of the benefit of the MED-mortality association, respectively), followed by triglyceride-rich lipoproteins (10.2%), adiposity (10.2%) and insulin resistance (7.4%), with lesser contributions (<3%) from other pathways including branched-chain amino acids, high-density lipoproteins, low-density lipoproteins, glycemic measures, and hypertension.

Conclusions

In the large-scale prospective Women's Health Study of 25,315 initially healthy US women followed for 25 years, higher MED intake was associated with approximately one fifth relative risk reduction in mortality. The inverse association was only partially explained by known novel and traditional cardiometabolic factors.

Branched Chain Amino Acids Are Associated with Physical Performance in Patients with End-Stage Liver Disease

Decreased circulating branched chain amino acids (BCAA) represent a prominent change in amino acid profiles in patients with end-stage liver disease (ESLD). These alterations are considered to contribute to sarcopenia and hepatic encephalopathy and may relate to poor prognosis. Here, we cross-sectionally analyzed the association between plasma BCAA levels and the severity of ESLD and muscle function in participants of the liver transplant subgroup of TransplantLines, enrolled between January 2017 and January 2020. Plasma BCAA levels were measured by nuclear magnetic resonance spectroscopy. Physical performance was analyzed with a hand grip strength test, 4 m walking test, sit-to-stand test, timed up and go test, standing balance test and clinical frailty scale. We included 92 patients (65% men). The Child Pugh Turcotte classification was significantly higher in the lowest sex-stratified BCAA tertile compared to the highest tertile (p = 0.015). The times for the sit-to-stand (r = -0.352, p < 0.05) and timed up and go tests (r = -0.472, p < 0.01) were inversely correlated with total BCAA levels. In conclusion, lower circulating BCAA are associated with the severity of liver disease and impaired muscle function. This suggests that BCAA may represent a useful prognostic marker in the staging of liver disease severity.

Longitudinal trajectories of branched chain amino acids through young adulthood and diabetes in later life

BACKGROUNDElevated circulating branched chain amino acids (BCAAs), measured at a single time point in middle life, are strongly associated with an increased risk of developing type 2 diabetes mellitus (DM). However, the longitudinal patterns of change in BCAAs through young adulthood and their association with DM in later life are unknown.METHODSWe serially measured BCAAs over 28 years in the Coronary Artery Risk Development in Young Adults (CARDIA) study, a prospective cohort of apparently healthy Black and White young adults at baseline. Trajectories of circulating BCAA concentrations from years 2-30 (for prevalent DM) or years 2-20 (for incident DM) were determined by latent class modeling.RESULTSAmong 3,081 apparently healthy young adults, trajectory analysis from years 2-30 revealed 3 distinct BCAA trajectory groups: low-stable (n = 1,427), moderate-stable (n = 1,384), and high-increasing (n = 270) groups. Male sex, higher body mass index, and higher atherogenic lipid fractions were more common in the moderate-stable and high-increasing groups. Higher risk of prevalent DM was associated with the moderate-stable (OR = 2.59, 95% CI: 1.90-3.55) and high-increasing (OR = 6.03, 95% CI: 3.86-9.43) BCAA trajectory groups in adjusted models. A separate trajectory group analysis from years 2-20 for incident DM after year 20 showed that moderate-stable and high-increasing trajectory groups were also significantly associated with higher risk of incident DM, after adjustment for clinical variables and glucose levels.CONCLUSIONBCAA levels track over a 28-year span in most young adults, but serial clinical metabolomic measurements identify subpopulations with rising levels associated with high risk of DM in later life.FUNDINGThis research was supported by the NIH, under grants R01 HL146844 (JTW) and T32 HL069771 (MRC). The CARDIA study is conducted and supported by the NIH National Heart, Lung, and Blood Institute in collaboration with the University of Alabama at Birmingham (HHSN268201800005I and HHSN268201800007I), Northwestern University (HHSN268201800003I), the University of Minnesota (HHSN268201800006I), and Kaiser Foundation Research Institute (HHSN268201800004I).

Mitochondrial pyruvate carrier inhibition initiates metabolic crosstalk to stimulate branched chain amino acid catabolism

OBJECTIVE

The mitochondrial pyruvate carrier (MPC) has emerged as a therapeutic target for treating insulin resistance, type 2 diabetes, and nonalcoholic steatohepatitis (NASH). We evaluated whether MPC inhibitors (MPCi) might correct impairments in branched chain amino acid (BCAA) catabolism, which are predictive of developing diabetes and NASH.

METHODS

Circulating BCAA concentrations were measured in people with NASH and type 2 diabetes, who participated in a recent randomized, placebo-controlled Phase IIB clinical trial to test the efficacy and safety of the MPCi MSDC-0602K (EMMINENCE; NCT02784444). In this 52-week trial, patients were randomly assigned to placebo (n = 94) or 250 mg MSDC-0602K (n = 101). Human hepatoma cell lines and mouse primary hepatocytes were used to test the direct effects of various MPCi on BCAA catabolism in vitro. Lastly, we investigated how hepatocyte-specific deletion of MPC2 affects BCAA metabolism in the liver of obese mice and MSDC-0602K treatment of Zucker diabetic fatty (ZDF) rats.

RESULTS

In patients with NASH, MSDC-0602K treatment, which led to marked improvements in insulin sensitivity and diabetes, had decreased plasma concentrations of BCAAs compared to baseline while placebo had no effect. The rate-limiting enzyme in BCAA catabolism is the mitochondrial branched chain ketoacid dehydrogenase (BCKDH), which is deactivated by phosphorylation. In multiple human hepatoma cell lines, MPCi markedly reduced BCKDH phosphorylation and stimulated branched chain keto acid catabolism; an effect that required the BCKDH phosphatase PPM1K. Mechanistically, the effects of MPCi were linked to activation of the energy sensing AMP-dependent protein kinase (AMPK) and mechanistic target of rapamycin (mTOR) kinase signaling cascades in vitro. BCKDH phosphorylation was reduced in liver of obese, hepatocyte-specific MPC2 knockout (LS-Mpc2-/-) mice compared to wild-type controls concomitant with activation of mTOR signaling in vivo. Finally, while MSDC-0602K treatment improved glucose homeostasis and increased the concentrations of some BCAA metabolites in ZDF rats, it did not lower plasma BCAA concentrations.

CONCLUSIONS

These data demonstrate novel cross talk between mitochondrial pyruvate and BCAA metabolism and suggest that MPC inhibition leads to lower plasma BCAA concentrations and BCKDH phosphorylation by activating the mTOR axis. However, the effects of MPCi on glucose homeostasis may be separable from its effects on BCAA concentrations.

Multimarkers of metabolic malnutrition and inflammation and their association with mortality risk in cardiac catheterisation patients: a prospective, longitudinal, observational, cohort study

BACKGROUND

Complex and incompletely understood metabolic dysfunction associated with inflammation and protein-energy wasting contribute to the increased mortality risk of older patients and those with chronic organ diseases affected by cachexia, sarcopenia, malnutrition, and frailty. However, these wasting syndromes have uncertain relevance for patients with cardiovascular disease or people at lower risk. Studies are hampered by imperfect objective clinical assessment tools for these intertwined metabolic malnutrition and inflammation syndromes. We aimed to assess, in two independent cohorts of patients who underwent cardiac catheterisation, the mortality risk associated with the metabolic vulnerability index (MVX), a multimarker derived from six simultaneously measured serum biomarkers plausibly linked to these dysmetabolic syndromes.

METHODS

In this prospective, longitudinal, observational study, we included patients aged ≥18 years recruited into the CATHGEN biorepository (Jan 2, 2001, to Dec 30, 2011) and the Intermountain Heart Collaborative Study (Sept 12, 2000, to Sept 21, 2006) who underwent coronary angiography and had clinical nuclear magnetic resonance metabolomic profiling done on frozen plasma obtained at catheterisation. We aggregated six mortality risk biomarkers (GlycA, small HDL, valine, leucine, isoleucine, and citrate concentrations) into sex-specific MVX multimarker scores using coefficients from predictive models for all-cause mortality in the CATHGEN cohort. We assessed associations of biomarkers and MVX with mortality in both cohorts using Cox proportional hazards models adjusted for 15 clinical covariates.

FINDINGS

We included 5876 participants from the CATHGEN biorepository and 2888 from the Intermountain Heart study. Median follow-up was 6·2 years (IQR 4·4-8·9) in CATHGEN and 8·2 years (6·9-9·2) in the Intermountain Heart study. The six nuclear magnetic resonance biomarkers and MVX made strong, independent contributions to 5-year mortality risk prediction in both cohorts (hazard ratio 2·18 [95% CI 2·03-2·34] in the CATHGEN cohort and 1·67 [1·50-1·87] in the Intermountain Heart cohort). CATHGEN subgroup analyses showed similar MVX associations in men and women, older and younger individuals, for death from cardiovascular or non-cardiovascular causes, and in patients with or without multiple comorbidities.

INTERPRETATION

MVX made a dominant contribution to mortality prediction in patients with cardiovascular disease and in low-risk subgroups without pre-existing disease, suggesting that metabolic malnutrition-inflammation syndromes might have a more universal role in survival than previously thought.

FUNDING

Labcorp.

Effect of behavioral weight-loss program on biomarkers of cardiometabolic disease risk: Heart Health Study randomized trial

OBJECTIVE

This study aimed to determine whether novel biomarkers of cardiometabolic health improve in response to a 12-month behavioral weight-loss intervention and to compare benefits of diet alone with diet plus physical activity for these biomarkers.

METHODS

Participants (N = 374) were randomized to either diet alone (DIET), diet plus 150 min/wk of prescribed moderate-intensity physical activity (DIET + PA150), or diet plus 250 min/wk of prescribed moderate-intensity physical activity (DIET + PA250). Biomarker concentrations were determined using nuclear magnetic resonance spectroscopy. Mixed models assessed for a time effect, group effect, or group by time interaction.

RESULTS

All groups significantly improved body weight (time: p < 0.0001), Lipoprotein Insulin Resistance Index score (time: p < 0.0001), Diabetes Risk Index score (time: p < 0.0001), branched-chain amino acid concentration (time: p < 0.0001), and GlycA concentration (time: p < 0.0001), with no group effect or group by time interactions.

CONCLUSIONS

All intervention groups prompted a notable beneficial change among biomarkers of insulin resistance and cardiometabolic health. However, the addition of at least moderate-intensity physical activity to a diet-only intervention did not provide any additional benefit. These findings highlight that an average weight loss of approximately 10% profoundly impacts biomarkers of insulin resistance and cardiometabolic disease in adults with overweight or obesity.

Bariatric surgery normalizes diabetes risk index by one month post-operation

AIM

The Diabetes risk index (DRI) is a composite of NMR-measured lipoproteins and branched chain amino acids predictive of diabetes mellitus development. Bariatric surgery is indicated in patients with severe obesity, many of whom are at high-risk for developing diabetes. Substantial weight loss occurs following bariatric surgery and sustained weight loss likely contributes to reductions in the development of diabetes and cardiovascular disease. However, some evidence suggests that bariatric surgical procedures themselves may contribute to reducing risk of these conditions independent of weight loss. We aimed to investigate DRI and its association with reductions in body weight and adiposity over one year following bariatric surgery.

METHODS

We examined 51 severely obese premenopausal women without diabetes. DRI, BMI, body weight and waist measurements were made before and at 1, 6 and 12 months after Roux-en-Y Gastric Bypass (RYGB) or Sleeve Gastrectomy. Values were compared to healthy women with normal BMI (18.5-24.9 kg/m2; n = 15).

RESULTS

Non-diabetic women with severe obesity (BMI 44.7 ± 6.2 kg/m2) exhibited significantly elevated DRI scores prior to surgery versus controls (35 [26, 39] vs 12 [1, 20]; p < 0.0001). At 1 month after surgery, BMI decreased 5.1 ± 1.1 kg/m2, but DRI decreased so that it no longer differed from that of normal BMI controls (1.9 [1, 17] vs control 12 [1, 20]; p = 0.35). Subjects continued to lose weight, whereas DRI remained similar, throughout follow-up with DRI 1.0 [1, 7] at 12 months. Changes in DRI did not correlate with changes in BMI, body weight or waist circumference at any time during follow-up. There was no difference in change in DRI between surgical procedures or pre-operative metabolic syndrome status.

CONCLUSIONS

Our analysis of DRI scores supports the capacity of bariatric surgery to reduce risk of developing diabetes in severely obese individuals. Our findings suggest that bariatric surgical techniques may have inherent effects that improve cardiometabolic risk independent of reductions in body weight or adiposity.

New Advances in Metabolic Syndrome, from Prevention to Treatment: The Role of Diet and Food

The definition of metabolic syndrome (MetS) has undergone several changes over the years due to the difficulty in establishing universal criteria for it. Underlying the disorders related to MetS is almost invariably a pro-inflammatory state related to altered glucose metabolism, which could lead to elevated cardiovascular risk. Indeed, the complications closely related to MetS are cardiovascular diseases (CVDs) and type 2 diabetes (T2D). It has been observed that the predisposition to metabolic syndrome is modulated by complex interactions between human microbiota, genetic factors, and diet. This review provides a summary of the last decade of literature related to three principal aspects of MetS: (i) the syndrome's definition and classification, pathophysiology, and treatment approaches; (ii) prediction and diagnosis underlying the biomarkers identified by means of advanced methodologies (NMR, LC/GC-MS, and LC, LC-MS); and (iii) the role of foods and food components in prevention and/or treatment of MetS, demonstrating a possible role of specific foods intake in the development of MetS.

Vantera Mediated Quantification of Urine Citrate and Creatinine: A New Technology to Assess Risk of Nephrolithiasis

Urine citrate is often used to identify patients at risk of recurrent nephrolithiasis or kidney stones. A high-throughput assay was developed to measure urine citrate and creatinine on the Vantera® Clinical Analyzer, a nuclear magnetic resonance (NMR) instrument designed for the clinical laboratory. Assay performance was evaluated and comparisons between the NMR and chemistry results were conducted. Linearity was demonstrated over a wide range of concentrations for citrate (6 and 2040 mg/L) and creatinine (2.8 and 1308 mg/dL). Intra-and inter-assay precision (%CV) ranged from 0.9 to 3.7% for citrate and 0.4 to 2.1% for creatinine. The correlation coefficients for the comparison between NMR and chemistry results were 0.98 (Y = 1.00X + 5.0) for citrate and 0.96 (Y = 0.968X + 0.97) for creatinine. The reference intervals for both analytes were confirmed. Ten endogenous and exogenous substances were tested and none were found to interfere with the assay results. In conclusion, the newly developed high-throughput NMR assay exhibited robust performance and generated results comparable to the currently utilized chemistry tests, thereby providing an alternative means to simultaneously quantify urine citrate and creatinine for clinical and research use. Furthermore, the NMR assay does not exhibit the same interference limitations as the chemistry tests and it enables multiplexing with other urine metabolite assays which saves time and costs.

Risk factors for cardiovascular disease among individuals with hepatic steatosis

Cardiovascular disease (CVD) is the leading cause of mortality in adults with hepatic steatosis (HS). However, risk factors for CVD in HS are unknown. We aimed to identify factors associated with coronary artery disease (CAD) and incident major adverse cardiovascular events (MACE) in individuals with HS. We performed a nested cohort study of adults with HS detected on coronary computed tomography in the PROspective Multicenter Imaging Study for Evaluation of chest pain (PROMISE) trial. Obstructive CAD was defined as ≥50% coronary stenosis. MACE included hospitalization for unstable angina, nonfatal myocardial infarction, or all-cause death. Multivariate modeling, adjusted for age, sex, atherosclerotic CVD (ASCVD) risk score and body mass index, identified factors associated with obstructive CAD. Cox regression, adjusted for ASCVD risk score, determined the predictors of MACE. A total of 959 of 3,756 (mean age 59.4 years, 55.0% men) had HS. Obstructive CAD was present in 15.2% (145 of 959). Male sex (adjusted odds ratio [aOR] = 1.83, 95% confidence interval [CI] 1.18-1.2.84; p = 0.007), ASCVD risk score (aOR = 1.05, 95% CI 1.03-1.07; p < 0.001), and n-terminal pro-b-type natriuretic peptide (NT-proBNP; aOR = 1.90, 95% CI 1.38-2.62; p < 0.001) were independently associated with obstructive CAD. In the 25-months median follow-up, MACE occurred in 4.4% (42 of 959). Sedentary lifestyle (adjusted hazard ratio [aHR] = 2.53, 95% CI 1.27-5.03; p = 0.008) and NT-proBNP (aOR = 1.50, 95% CI 1.01-2.25; p = 0.046) independently predicted MACE. Furthermore, the risk of MACE increased by 3% for every 1% increase in ASCVD risk score (aHR = 1.03, 95% CI 1.01-1.05; p = 0.02). Conclusion: In individuals with HS, male sex, NT-pro-BNP, and ASCVD risk score are associated with obstructive CAD. Furthermore, ASCVD, NT-proBNP, and sedentary lifestyle are independent predictors of MACE. These factors, with further validation, may help risk-stratify adults with HS for incident CAD and MACE.

Nut consumption is associated with a shift of the NMR lipoprotein subfraction profile to a less atherogenic pattern among older individuals at high CVD risk

BACKGROUND

Scientific evidence has accumulated on the beneficial effects of nut consumption on cardiovascular risk and cholesterol reduction, but few studies have examined the effects of nuts on advanced measures of lipoprotein atherogenicity determined by nuclear magnetic resonance (NMR) spectroscopy. We analyzed associations between the amount and type of of nuts consumed and advanced measures of lipoprotein atherogenity and insulin resistance in older individuals at high cardiovascular risk.

METHODS

The present observational study was carried out within the framework of the Prevención con Dieta Mediterránea (PREDIMED) trial. Cross-sectional and longitudinal analyses after 1-year of follow-up were conducted in 196 men and women recruited in the PREDIMED-Reus (Spain) center. Dietary intake was assessed using a validated semi-quantitative food questionnaire. Baseline and 1-year fasting plasma lipoprotein and metabolite profiling were performed in plasma using NMR spectra Vantera^® Clinical Analyzer. Associations by tertiles of nut consumption between baseline and 1-year changes and advanced measures of lipoprotein atherogenicity, branched chain amminoacids, and measures of insulin resistance were tested by multivariable-adjusted ANCOVA models.

RESULTS

Compared to paticipants in the bottom tertile, those in the top tertile of total nut consumption showed higher levels of large HDL particles and HDL-cholesterol, lower levels of branched-chain amino acids (BCAA) and GlycA, and reduced lipoprotein insulin resistance and diabetes risk index. Participants in the top tertile of walnut consumption disclosed lower levels of very large VLDL, total LDL particles, LDL-cholesterol, and GlycA. Participants in the top tertile of non-walnut nut consumption displayed higher levels of total HDL particles, HDL-cholesterol and apoliporotein A1, lower BCAA and GlycA, and reduced lipoprotein insulin resistance. Participants in the top tertile of 1-year changes in walnut consumption showed increases in medium-sized HDL particles in comparison to the bottom tertile.

CONCLUSIONS

In older individuals at high cardiovascular risk, increasing nut consumption was associated with a shift of the NMR lipoprotein subfraction profile to a less atherogenic pattern, as well as lower circulating concentrations of BCAA and decreased insulin resistance. These results provide novel mechanistic insight into the cardiovascular benefit of nut consumption. Trial registration ISRCTN35739639; registration date: 05/10/2005; recruitment start date 01/10/2003.

Associations of clinical and circulating metabolic biomarkers with low physical fitness and function in adults with chronic lymphocytic leukemia

Many patients with chronic lymphocytic leukemia (CLL) experience physical dysfunction and low overall fitness. It remains unknown what factors drive CLL physical dysfunction. We assessed physical function and metabolic lipoprotein panels in 106 patients with CLL. In univariate analyses of clinical factors, a longer time since diagnosis was associated with a higher likelihood of dysfunctional aerobic fitness (OR = 3.56, 95% CI: 1.37–9.22; p = 0.002) and physical performance (SPPB: OR = 2.03, 95% CI: 1.20–3.44; p = 0.004). Having received treatment was associated with a higher likelihood of dysfunctional aerobic fitness (OR = 1.57, 95% CI: 1.02–2.40; p = 0.036), SPPB (OR = 1.85, 95% CI: 1.13–3.03; p = 0.011) and grip strength (OR = 1.67, 95% CI: 1.10–2.55; p = 0.015). We found that several small HDL particle parameters, higher levels of citrate (OR = 2.01, 95% CI: 1.22–3.31; p = 0.030), and lower levels of hemoglobin (OR = 0.50, 95% CI: 0.31–0.82; p = 0.030) were associated with a higher likelihood of dysfunctional aerobic fitness. Multivariable least absolute shrinkage and selection operator (LASSO)-penalized regression analyses using variable importance measures (VIM) showed that 7.8-nm HDL particles (VIM = 1.000) and total HDL particle levels (VIM = 1.000) were more informative than clinical measures for the odds of dysfunctional aerobic fitness and 6-min walk functional fitness, respectively, while 10.3-nm HDL particles (VIM = 0.383) were more informative for grip strength. Time since diagnosis (VIM = 0.680) and having received treatment (VIM = 0.490) were more informative than lipoprotein measures for the odds of having dysfunctional SPPB. Taken together, we establish significant relationships between clinical and metabolic factors and physical characteristics that might prompt early use of ancillary support services.

Circulating total and intact GDF-15 levels are not altered in response to weight loss induced by liraglutide or lorcaserin treatment in humans with obesity

BACKGROUND

Growth differentiation factor 15 (GDF-15) is a stress-response cytokine proposed to be associated with body weight regulation.

AIMS

The primary aim was to investigate changes of circulating intact GDF-15 (wildtype, non-carrier of the rs1058587 polymorphism coding for the H2O2D mutation) and total GDF-15 (measured irrespective of the mutation) in response to liraglutide (GLP-1 receptor agonist) and lorcaserin (5-HT2C receptor agonist), two pharmacologic agents that induce food intake and weight reduction. In addition, we perform exploratory correlations of total and intact GDF-15 with clinical, hormonal and metabolo-lipidomic parameters in humans with obesity.

MATERIALS AND METHODS

We utilized two studies: 1) Study 1, a randomized, double-blinded, cross-over trial of liraglutide and placebo administration for 5 weeks in subjects with obesity (n = 20; BMI = 35.6 ± 5.9 kg/m2), in escalating doses starting at 0.6 mg/day on week 1 and increased every week, up to the highest dose of 3.0 mg/day during week 5. b) Study 2, a randomized, double-blinded trial of lorcaserin 10 mg twice daily, or placebo for 12-weeks in humans with obesity (n = 34 BMI = 37.4 ± 6.1 kg/m2). Total and intact GDF-15 levels were measured with novel enzyme-linked immunosorbent assays and the metabolomics and lipidomics analysis was performed with nuclear magnetic resonance spectroscopy.

RESULTS

Total and intact GDF-15 were positively correlated with diabetes risk index and trimethylamine N-oxide and negatively with eGFR. Despite significant changes in body weight, total and intact GDF-15 were not altered in response to liraglutide or lorcaserin treatment in subjects with obesity.

CONCLUSIONS

Total and intact GDF-15 levels are not altered in response to liraglutide or lorcaserin therapy and are thus not directly involved in the metabolic feedback loop pathways downstream of GLP1 or 5-HT2C receptor agonists. Since neither total nor intact GDF-15 levels were altered in response to weight loss, future studies are needed to elucidate the pathways activated by GDF-15 in humans and its role, if any, in body weight regulation and energy homeostasis.

Differential Effects of Amount, Intensity, and Mode of Exercise Training on Insulin Sensitivity and Glucose Homeostasis: A Narrative Review

As type 2 diabetes remains a leading cause of morbidity and mortality, identifying the most appropriate preventive treatment early in the development of disease is an important public health matter. In general, lifestyle interventions incorporating exercise and weight loss via caloric restriction improve cardiometabolic risk by impacting several key markers of insulin sensitivity and glucose homeostasis. However, variations in the effects of specific types of exercise interventions on these markers have led to conflicting results surrounding the optimal amount, intensity, and mode of exercise for optimal effects. Moreover, the addition of weight loss via caloric restriction to exercise interventions appears to differentially impact changes in body composition, metabolism, and insulin sensitivity compared to exercise alone. Determining the optimal amount, intensity, and mode of exercise having the most beneficial impact on glycemic status is both: (1) clinically important to provide guidelines for appropriate exercise prescription; and (2) physiologically important to understand the pathways by which exercise-with and without weight loss-impacts glycemic status to enhance precision lifestyle medicine. Thus, the purposes of this narrative review are to: (1) summarize findings from the three Studies of a Targeted Risk Reduction Intervention through Defined Exercise (STRRIDE) randomized trials regarding the differential effects of exercise amount, intensity, and mode on insulin action and glucose homeostasis markers; and (2) compare the STRRIDE findings to other published dose-response exercise trials in order to piece together the various physiologic pathways by which specific exercise interventions-with or without weight loss-impact glycemic status.

Association of Modifiable Lifestyle Factors with Plasma Branched-Chain Amino Acid Metabolites in Women

BACKGROUND

Circulating branched-chain amino acids (BCAAs-isoleucine, leucine, and valine) are strongly associated with higher risk of incident type 2 diabetes (T2D); however, determinants of elevated fasting BCAA concentrations are largely unknown.

OBJECTIVES

We aimed to characterize the modifiable lifestyle factors related to plasma BCAAs.

METHODS

We performed a cross-sectional analysis among n = 18,897 women (mean ± SD age: 54.9 ± 7.2 y) in the Women's Health Study, free of T2D and cardiovascular disease at baseline blood draw. Lifestyle factors, weight, and height were self-reported via questionnaire, including smoking status, alcohol, leisure-time physical activity (LTPA), diet quality scores [2010 Alternative Healthy Eating Index (without alcohol) (aHEI); alternate Mediterranean Diet (aMED)], and dietary sources of BCAAs. Plasma BCAAs were quantified via NMR spectroscopy. We calculated multivariable-adjusted percentage mean differences (95% CIs) and P values for linear trend of BCAAs stratified by categoric lifestyle factors. We estimated R2 from univariate cubic spline regression models to estimate the variability in BCAAs explained.

RESULTS

Compared with women with BMI (in kg/m2) <25.0, BCAAs were 8.6% (95% CI: 8.0%, 9.3%), 15.3% (95% CI: 14.4%, 16.3%), and 21.0% (95% CI: 18.2%, 23.9%) higher for the BMI strata 25.0-29.9, 30.0-39.9, and ≥40.0, respectively (P-trend < 0.0001). Women with higher LTPA and higher alcohol intake compared with lower had modestly (∼1%) lower plasma BCAAs (P-trend = 0.014 and 0.0003, respectively). Differences in smoking status, aHEI, and aMED score were not related to plasma BCAAs. Women with higher dietary BCAAs had dose-response higher plasma BCAA concentrations, 3.4% (95% CI: 2.5%, 4.4%) higher when comparing the highest with the lowest quintile (P-trend < 0.0001). BMI explained 11.6% of the variability of BCAAs, whereas other factors explained between 0.1% and 1%.

CONCLUSIONS

Our findings among a large cohort of US women indicate that BMI, but less so diet, physical activity, and other lifestyle factors, is related to plasma BCAAs.This trial was registered at clinicaltrials.gov as NCT00000479.

Nuclear Magnetic Resonance-Measured Ionized Magnesium Is Inversely Associated with Type 2 Diabetes in the Insulin Resistance Atherosclerosis Study

The aims were to optimize a nuclear magnetic resonance (NMR)-based assay for quantifying ionized or free magnesium and investigate its association with type 2 diabetes (T2D). A high-throughput, ionized magnesium assay was optimized and evaluated. Plasma magnesium was quantified, and associations with T2D were ascertained in Insulin Resistance Atherosclerosis Study (IRAS) participants. Coefficients of variation for the ionized magnesium assay ranged from 0.7−1.5% for intra-assay and 4.2−4.7% for inter-assay precision. In IRAS (n = 1342), ionized magnesium was significantly lower in subjects with prediabetes and T2D than in normoglycemic subjects, and lower in participants with T2D than those with prediabetes (p < 0.0001). Cross-sectional regression analyses revealed that magnesium was associated with T2D at baseline in models adjusted for multiple clinical risk factors (p = 0.032). This association appeared to be modified by sex, in such a way that the associations were present in women (OR = 0.54 (95% CI 0.37−0.79), p = 0.0015) and not in men (OR = 0.98 (95% CI 0.71−1.35), p = 0.90). Longitudinal regression analyses revealed an inverse association between magnesium and future T2D in the total population (p = 0.035) that was attenuated by LP-IR (p = 0.22). No interactions were detected between magnesium and age, race, BMI, glucose, insulin, triglycerides, or LPIR for the prospective association with future T2D. However, a significant interaction between magnesium and sex was present, now with a trend for an association in men (OR = 0.75 (95% CI 0.55−1.02), p = 0.065 and absence of an association in women (OR = 1.01 (0.76−1.33), p = 0.97). Conclusions: lower ionized magnesium, as measured by an NMR-based assay optimized for accuracy and precision, was associated cross-sectionally with T2D at baseline and longitudinally with incident T2D in IRAS.

Profoundly Disturbed Lipoproteins in Cirrhotic Patients: Role of Lipoprotein-Z, a Hepatotoxic LDL-like Lipoprotein

Detailed information regarding lipoprotein concentrations and subfractions in cirrhotic patients before and after orthotopic liver transplantation (OLT) is lacking. Lipoprotein-Z (LP-Z) is a recently characterised abnormal, hepatotoxic free cholesterol-rich low-density lipoprotein (LDL)-like lipoprotein. We determined the lipoprotein profiles, including LP-Z, in cirrhotic patients and OLT recipients and assessed the prognostic significance of LP-Z on the OLT waiting list. We performed analyses in cirrhotic transplant candidates and non-cirrhotic OLT recipients. A population-based cohort was used as reference. The setting was a University hospital. Lipoprotein particle concentrations and subfractions were measured by nuclear magnetic resonance spectroscopy. In the cirrhotic patients (N = 130), most measures of triglyceride-rich lipoproteins (TRL), LDL, and high-density lipoproteins (HDL) were much lower compared to the OLT recipients (N = 372) and controls (N = 6027) (p < 0.01). In the OLT recipients, many lipoprotein variables were modestly lower, but HDL-cholesterol, triglycerides, and TRL and HDL size were greater vs. the control population. LP-Z was measurable in 40 cirrhotic patients and 3 OLT recipients (30.8% vs. 0.8%, p < 0.001). The cirrhotic patients with measurable LP-Z levels had profoundly lower HDL-cholesterol and particle concentrations (p < 0.001), and worse Child Pugh Turcotte classifications and MELD scores. The presence of LP-Z (adjusted for age, sex, and MELD score) predicted worse survival in cirrhotic patients (HR per 1 LnSD increment: 1.11, 95%CI 1.03−1.19, p = 0.003). In conclusion, cirrhotic patients have considerably lower plasma concentrations of all major lipoprotein classes with changes in lipoprotein subfraction distribution. After OLT, these lipoprotein abnormalities are in part reversed. LP-Z is associated with cirrhosis. Its presence may translate in disturbed HDL metabolism and worse survival.

Branched Chain Amino Acids are associated with Metabolic Complications in Liver Transplant Recipients

BACKGROUND

Obesity, dyslipidemia and type 2 diabetes (T2D) contribute substantially to increased cardiovascular morbidity and mortality in patients after orthotopic liver transplantation (OLTx). Elevated plasma branched chain amino acids (BCAA) are linked to metabolic disturbances and cardiovascular disease (CVD) risk profiles in several non-OLTx populations.

METHODS

Cross-sectional analysis of liver transplant recipients from TransplantLines, a single-center biobank and cohort study. BCAA plasma levels were measured by means of nuclear-magnetic resonance spectroscopy. CVD and cardiometabolic factors were collected by using data from electronic patient records. Associations were determined between BCAA plasma levels and T2D, Metabolic Syndrome (MetS), CVD as well as mTOR inhibition in liver transplant recipients.

RESULTS

336 Patients were divided into sex-stratified tertiles of total BCAA. MetS (P<0.001) and T2D (P=0.002) were significantly more frequent in subjects in the highest BCAA tertile. In logistic regression analyses, the multivariable adjusted odds ratio (OR) per 1 standard deviation increase in BCAA was 1.68 (95%CI: 1.18-2.20, P=0.003) for MetS and 1.60 (95%CI: 1.14-2.23, P=0.006) for T2D. Use of Sirolimus (mTOR inhibitor) was significantly associated with higher BCAA plasma levels, independent of age, sex, time after OLTx, MetS and other immunosuppressive medication (adjusted P=0.002).

CONCLUSION

Elevated BCAA plasma levels are associated with T2D, MetS and use of Sirolimus in liver transplant recipients. BCAA plasma levels may represent a valuable biomarker for cardiometabolic complications after OLTx.

Calorie restriction improves lipid-related emerging cardiometabolic risk factors in healthy adults without obesity: Distinct influences of BMI and sex from CALERIE™ a multicentre, phase 2, randomised controlled trial

BACKGROUND

For many cardiovascular risk factors there is no lower limit to which further reduction will result in decreased disease risk; this includes values within ranges considered normal for healthy adults. This seems to be true for new emerging metabolic risk factors identified by innovative technological advances. Further, there seems to be ever evolving evidence of differential responses to lifestyle interventions by sex and body compositions in the normal range. In this secondary analysis, we had the opportunity to test these principles for newly identified molecular biomarkers of cardiometabolic risk in a young (21-50 years), normal weight healthy population undergoing calorie restriction for two years.

METHODS

The Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE™) was a 24-month, multicenter, randomized controlled trial (May 2007-November 2012) in healthy, adults without obesity to evaluate the potential for calorie restriction (CR) to promote anti-aging adaptations, including those associated with disease risk. 218 participants (age 37.9 ± 7.2 years and body mass index (BMI) 25.1 ± 1.7 kg/m², mean±SD) were randomized 2:1 to 24 months of CR (prescribed as 25% reduction from baseline calorie intake) versus ad libitum (AL). Fasting plasma from baseline, 12, and 24 months was used for assessments of lipoproteins, metabolites, and inflammatory markers using nuclear magnetic resonance spectroscopy.

FINDINGS

Averaging 11.9% CR, the CR group had reductions at 12 and 24 months in the cardiovascular disease risk markers, apolipoprotein B and GlycA, and risks for insulin resistance and type 2 diabetes-Lipoprotein Insulin Resistance Index and Diabetes Risk Index (all P_CRvsAL ≤0.0009). Insulin resistance and diabetes risk improvements resulted from CR-induced alterations in lipoproteins, specifically reductions in triglyceride-rich lipoprotein particles and low-density lipoprotein particles, a shift to larger high-density lipoprotein particles (more effective cholesterol transporters), and reductions in branched chain amino acids (BCAAs) (all P_CRvsAL ≤0.004). These CR responses were more pronounced in overweight than normal weight participants and greater in men than women.

INTERPRETATION

In normal to slightly overweight adults without overt risk factors or disease, 12 months of ∼12% CR improved newly identified risk markers for atherosclerotic cardiovascular disease, insulin resistance and type 2 diabetes. These markers suggest that CR improves risks by reducing inflammation and BCAAs and shifting lipoproteins from atherogenic to cholesterol transporting. Additionally, these improvements are greater for men and for those with greater BMIs indicating sex and BMI-influences merit attention in future investigations of lifestyle-mediated improvements in disease risk factors.

FUNDING

The CALERIE™ trial design and implementation were supported by a National Institutes of Health (NIH) U-grant provided to four institutions, the three intervention sites and a coordinating center (U01 AG022132, U01 AG020478, U01 AG020487 U01 AG020480). For this secondary analysis including sample acquisition and processing, data analysis and interpretation, additional funding was provided by the NIH to authors as follows: R01 AG054840 (MO, VBK); R33 AG070455 (KMH, DCP, MB, SBR, CKM, LMR, SKD, CFP, CJR, WEK); P30 DK072476 (CKM, LMR); and U54 GM104940 (CKM, LMR).

Daily transient coating of the intestine leads to weight loss and improved glucose tolerance

INTRODUCTION

Roux-en-Y gastric bypass surgery (RYGB) has been shown to be the gold standard treatment for obesity associated type-2-diabetes (T2D), however many T2D patients do not qualify or are reluctant to proceed with surgery due to its potential risks and permanent changes to GI anatomy. We have previously described a novel oral formulation, LuCI, that provides a transient coating of the proximal bowel and mimics the effects of RYGB. Herein, we aim to investigate the outcome of chronic LuCI administration on weight and glucose homeostasis.

METHODS

Sprague-Dawley rats on a high fat diet achieving diet-induced obesity (DIO) received 5 weeks of daily LuCI or normal saline as control (n = 8/group). Daily weights and glucose tolerance were monitored throughout the experiment. At 5 weeks, systemic blood was sampled through a surgically placed jugular vein catheter, before and during an intestinal glucose bolus, to investigate changes in key hormones involved in glucose metabolism. To elucidate the effects of LuCI on nutrient absorption, fecal output and food intake were measured simultaneously with the analysis of homogenized stool samples performed using bomb calorimetry.

RESULTS

At 5 weeks, LuCI animals weighted 8.3% less and had lower fasting glucose levels than Controls (77.6 ± 3.8 mg/dl vs. 99.1 ± 2.7 mg/dl, P < 0.001). LuCI-treated animals had lower baseline insulin and HOMA-IR. Post-prandially, LuCI group had increased GLP-1 and GIP secretion following a glucose challenge. Serum lipid analysis revealed lowered LDL levels highlighting the potential to not only improve glucose control but also modify cardiovascular risk. We then investigated whether LuCI's effect on proximal bowel exclusion may play a role in energy balance. Bomb calorimetry analysis suggested that LuCI reduced calorie absorption with no difference in caloric consumption.

CONCLUSION

We demonstrated that LuCI recapitulates the physical and hormonal changes seen after RYGB and can ameliorate weight gain and improve insulin sensitivity in a DIO rat model. Since LuCI's effect is transient and without systemic absorption, LuCI has the potential to be a novel therapy for overweight or obese T2D patients.

Lipoprotein particle alterations due to androgen therapy in individuals with dyskeratosis congenita

Background

Dyskeratosis congenita (DC) is a telomere biology disorder associated with high rates of bone marrow failure (BMF) and other medical complications. Oral androgens are successfully used to treat BMF in DC but often have significant side effects, including elevation of serum lipids. This study sought to determine the extent to which oral androgen therapy altered lipid and lipoprotein levels.

Methods

Nuclear magnetic resonance (NMR) was used to evaluate serum lipid profiles, and lipoprotein particle number and size in nine androgen-treated individuals with DC, 45 untreated individuals with DC, 72 unaffected relatives of DC patients, and 19 untreated individuals with a different inherited BMF syndrome, Fanconi anaemia (FA).

Findings

Androgen-treated individuals with DC had significantly decreased serum HDL cholesterol, HDL particle number and HDL particle size (p < 0·001, p < 0·001 and p < 0·001, respectively); significantly increased serum LDL cholesterol and LDL particle number (p < 0·001, p < 0·001, respectively), decreased apoA-I and increased apoB (p < 0⋅001, p < 0⋅05 respectively) when compared with untreated individuals with DC. There were no significant lipid profile differences between untreated DC and untreated FA participants; or between untreated DC participants and their unaffected relatives. Branched chain amino acids and lipoprotein insulin resistance were not significantly different with androgen treatment. GlycA, an inflammatory acute phase reactant, was significantly increased with androgen treatment (p < 0⋅001).

Interpretation

Androgen treatment in DC creates an atherogenic lipoprotein profile, raising concern for the potential of elevated cardiovascular disease risk. Clinical guidelines for individuals on androgens for DC-related BMF should include cardiovascular disease monitoring. These findings could be relevant in individuals treated with androgen for other indications.

Funding

Intramural research programs of the Division of Cancer Epidemiology and Genetics of the National Cancer Institute and National Heart, Lung, and Blood Institute.

A metabolomic index based on lipoprotein subfractions and branched chain amino acids is associated with incident hypertension

OBJECTIVE

The present study aims to evaluate the performance of the Diabetes Risk Index (DRI), a metabolomic index based on lipoprotein particles and branched chain amino acids, on the incidence of newly developed hypertension in a large community dwelling cohort.

METHODS

The DRI was calculated by combining 6 lipoprotein parameters [sizes of very-low-density lipoprotein (VLDL), low-density lipoprotein (LDL) and high-density lipoprotein (HDL), concentrations of large VLDL, small LDL, and large HDL particles], and the concentrations of valine and leucine. DRI scores were estimated in 4169 participants from the PREVEND prospective cohort. Cox proportional hazards regression was used to evaluate the association of DRI scores with incident hypertension.

RESULTS

During a median follow-up of 8.6 years, 924 new hypertension cases were ascertained. In analyses adjusted for age and sex, there was a significant association between DRI and incident hypertension with a hazard ratio (HR) per 1 SD increase of 1.45 (95% CI 1.36,1.54; p < 0.001). After additional adjustment for traditional risk factors, the HR remained significant (HR_adj 1.21, 95% CI 1.10, 1.33, p <0.001). Likewise, subjects in the top quartile of DRI presented with a higher risk of hypertension (HR_adj 1.64, 95% CI 1.28, 2.10, p <0.001). Furthermore, the net reclassification improvement assessment improved after the addition of DRI to a traditional risk model (p <0.001), allowing proper reclassification of 34% of the participants.

CONCLUSION

Higher DRI scores were associated with an increased risk of incident hypertension. Such association was independent of traditional clinical risk factors for hypertension.

Branched-Chain Amino Acids and Risk of Breast Cancer

Background

Circulating branched-chain amino acid (BCAA) levels reflect metabolic health and dietary intake. However, associations with breast cancer are unclear.

Methods

We evaluated circulating BCAA levels and breast cancer risk within the Nurses’ Health Study (NHS) and NHSII (1997 cases and 1997 controls). A total of 592 NHS women donated 2 blood samples 10 years apart. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) of breast cancer risk in multivariable logistic regression models. We conducted an external validation in 1765 cases in the Women’s Health Study (WHS). All statistical tests were 2-sided.

Results

Among NHSII participants (predominantly premenopausal at blood collection), elevated circulating BCAA levels were associated with lower breast cancer risk (eg, isoleucine highest vs lowest quartile, multivariable OR = 0.86, 95% CI = 0.65 to 1.13, P_trend = .20), with statistically significant linear trends among fasting samples (eg, isoleucine OR = 0.74, 95% CI = 0.53 to 1.05, P_trend = .05). In contrast, among postmenopausal women, proximate measures (<10 years from blood draw) were associated with increased breast cancer risk (eg, isoleucine OR = 1.63, 95% CI = 1.12 to 2.39, P_trend = .01), with stronger associations among fasting samples (OR = 1.73, 95% CI = 1.15 to 2.61, P_trend = .01). Distant measures (10-20 years since blood draw) were not associated with risk. In the WHS, a positive association was observed for distant measures of leucine among postmenopausal women (OR = 1.23, 95% CI = 0.96 to 1.58, P_trend = .04).

Conclusions

No statistically significant associations between BCAA levels and breast cancer risk were consistent across NHS and WHS or NHSII and WHS. Elevated circulating BCAA levels were associated with lower breast cancer risk among predominantly premenopausal NHSII women and higher risk among postmenopausal women in NHS but not in the WHS. Additional studies are needed to understand this complex relationship.

The Association between Branched-Chain Amino Acids (BCAAs) and Cardiometabolic Risk Factors in Middle-Aged Caucasian Women Stratified According to Glycemic Status

We examined the glycemic status-stratified relationships between total serum branched-chain amino acid (BCAA) concentrations and cardiometabolic risk factors in middle-aged Caucasian women. The study included 349 women divided into 2 subgroups: a normoglycemic group (NG, n = 184) and a dysglycemic group (DG, n = 165). Blood samples, anthropometric parameters, and blood pressure were measured. HOMA-IR, albumin-corrected calcium (CCa), and fatty liver index (FLI) were calculated. BCAA concentrations were higher in the women with dysglycemia. BCAAs moderately correlated with BMI and FLI in the NG group and with BMI, FLI, total calcium (TCa), CCa, HbA1c, TG/HDL-C, and HDL-C in the DG group. After adjusting for age and BMI, correlations for TCa, CCa, HbA1c, HDL-C, and TG/HDL-C remained significant. The coexistence of increased BCAAs with dysglycemic status was associated with markedly higher concentrations of TCa, CCa, HbA1c, and TG, which were not observed in the DG women with low level of BCAAs. Multiple regression showed that TCa or CCa, age and BCAAs were significantly associated with HbA1c independently of BMI only in the DG group. We conclude that dysglycemia in particular predisposes women to a significant relationship between total BCAAs and circulating calcium and HbA1c, and that these relationships are independent of BMI and may reflect the pathophysiological calcium-dependent mechanisms connecting BCAAs with metabolic disturbances.

The NIH Lipo-COVID Study: A Pilot NMR Investigation of Lipoprotein Subfractions and Other Metabolites in Patients with Severe COVID-19

A complex interplay exists between plasma lipoproteins and inflammation, as evidenced from studies on atherosclerosis. Alterations in plasma lipoprotein levels in the context of infectious diseases, particularly respiratory viral infections, such as SARS-CoV-2, have become of great interest in recent years, due to their potential utility as prognostic markers. Patients with severe COVID-19 have been reported to have low levels of total cholesterol, HDL-cholesterol, and LDL-cholesterol, but elevated levels of triglycerides. However, a detailed characterization of the particle counts and sizes of the different plasma lipoproteins in patients with COVID-19 has yet to be reported. In this pilot study, NMR spectroscopy was used to characterize lipoprotein particle numbers and sizes, and various metabolites, in 32 patients with severe COVID-19 admitted to the intensive care unit. Our study revealed markedly reduced HDL particle (HDL-P) numbers at presentation, especially low numbers of small HDL-P (S-HDL-P), and high counts of triglyceride-rich lipoprotein particle (TRL-P), particularly the very small and small TRL subfractions. Moreover, patients with severe COVID-19 were found to have remarkably elevated GlycA levels, and elevated levels of branched-chain amino acids and beta-hydroxybutyrate. Finally, we detected elevated levels of lipoproteins X and Z in most participants, which are distinct markers of hepatic dysfunction, and that was a novel finding.

Mahalanobis distance, a novel statistical proxy of homeostasis loss is longitudinally associated with risk of type 2 diabetes

Background

The potential role of individual plasma biomarkers in the pathogenesis of type 2 diabetes (T2D) has been broadly studied, but the impact of biomarkers interaction remains underexplored. Recently, the Mahalanobis distance (MD) of plasma biomarkers has been proposed as a proxy of physiological dysregulation. Here we aimed to investigate whether the MD calculated from circulating biomarkers is prospectively associated with development of T2D.

Methods

We calculated the MD of the Principal Components (PCs) integrating the information of 32 circulating biomarkers (comprising inflammation, glycemic, lipid, microbiome and one-carbon metabolism) measured in 6247 participants of the PREVEND study without T2D at baseline. Cox proportional-hazards regression analyses were performed to study the association of MD with T2D development.

Findings

After a median follow-up of 7·3 years, 312 subjects developed T2D. The overall MD (mean (SD)) was higher in subjects who developed T2D compared to those who did not: 35·65 (26·67) and 30.75 (27·57), respectively (P = 0·002). The highest hazard ratio (HR) was obtained using the MD calculated from the first 31 PCs (per 1 log-unit increment) (1·72 (95% CI 1·42,2·07), P < 0·001). Such associations remained after the adjustment for age, sex, plasma glucose, parental history of T2D, lipids, blood pressure medication, and BMI (HR_adj 1·37 (95% CI 1·11,1·70), P = 0·004).

Interpretation

Our results are in line with the premise that MD represents an estimate of homeostasis loss. This study suggests that MD is able to provide information about physiological dysregulation also in the pathogenesis of T2D.

Funding

The Dutch Kidney Foundation (Grant E.033).

Association of Plasma Branched-Chain Amino Acid With Biomarkers of Inflammation and Lipid Metabolism in Women

BACKGROUND

Branched-chain amino acids (BCAAs; isoleucine, leucine, and valine) correlate with insulin resistance and poor glucose control, which may in part explain associations between type 2 diabetes and cardiovascular disease. However, the relationships of BCAAs with other cardiometabolic pathways, including inflammation and dyslipidemia, are unclear. We hypothesized that plasma BCAAs would correlate with multiple pathways of cardiometabolic dysfunction.

METHODS

We conducted a cross-sectional analysis among 19 472 participants (mean age=54.9 years, SD=7.2 years) in the Women's Health Study without a history of type 2 diabetes, cardiovascular disease, or cancer. We quantified the concentrations of individual biomarkers of inflammation and lipids, across quartiles of BCAAs, adjusting for age, smoking, body mass index, physical activity, and other established cardiovascular disease risk factors at blood draw.

RESULTS

Women in the highest versus lowest quartiles of plasma BCAAs had higher inflammatory markers including high-sensitivity C-reactive protein (multivariable-adjusted means: 1.96 versus 1.43 mg/L), fibrinogen (367 versus 362 mg/dL), soluble intercellular cell adhesion molecule-1 (361 versus 353 ng/mL), and glycoprotein acetylation (407 versus 371 µmol/L; P trend=0.0002 for fibrinogen; P<0.0001 for others). Similarly for lipids, women with higher BCAAs had lower HDL-C (high-density lipoprotein cholesterol; 49.0 versus 55.0 mg/dL), and higher triglycerides (143 versus 114 mg/dL), LDL-C (low-density lipoprotein cholesterol; 133 versus 124 mg/dL), and lipoprotein insulin resistance score (52.6 versus 37.3; all: P<0.0001). Similar associations with these biomarkers were observed in isoleucine, leucine, and valine, respectively.

CONCLUSIONS

Higher circulating BCAA concentrations are associated with adverse profiles of biomarkers of inflammation and dyslipidemia independent of established cardiovascular disease risk factors, and thus, may reflect poorer cardiometabolic health through multiple pathways. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT00000479.

Integrative Modeling of Plasma Metabolic and Lipoprotein Biomarkers of SARS-CoV-2 Infection in Spanish and Australian COVID-19 Patient Cohorts

Quantitative plasma lipoprotein and metabolite profiles were measured on an autonomous community of the Basque Country (Spain) cohort consisting of hospitalized COVID-19 patients (n = 72) and a matched control group (n = 75) and a Western Australian (WA) cohort consisting of (n = 17) SARS-CoV-2 positives and (n = 20) healthy controls using 600 MHz ¹H nuclear magnetic resonance (NMR) spectroscopy. Spanish samples were measured in two laboratories using one-dimensional (1D) solvent-suppressed and T₂-filtered methods with in vitro diagnostic quantification of lipoproteins and metabolites. SARS-CoV-2 positive patients and healthy controls from both populations were modeled and cross-projected to estimate the biological similarities and validate biomarkers. Using the top 15 most discriminatory variables enabled construction of a cross-predictive model with 100% sensitivity and specificity (within populations) and 100% sensitivity and 82% specificity (between populations). Minor differences were observed between the control metabolic variables in the two cohorts, but the lipoproteins were virtually indistinguishable. We observed highly significant infection-related reductions in high-density lipoprotein (HDL) subfraction 4 phospholipids, apolipoproteins A1 and A2,that have previously been associated with negative regulation of blood coagulation and fibrinolysis. The Spanish and Australian diagnostic SARS-CoV-2 biomarkers were mathematically and biologically equivalent, demonstrating that NMR-based technologies are suitable for the study of the comparative pathology of COVID-19 via plasma phenotyping.

Circulating Trimethylamine N-Oxide Is Associated with Increased Risk of Cardiovascular Mortality in Type-2 Diabetes: Results from a Dutch Diabetes Cohort (ZODIAC-59)

Trimethylamine N-oxide (TMAO), a novel cardiovascular (CV) disease and mortality risk marker, is a gut microbiota-derived metabolite as well. Recently, plasma concentrations of branched-chain amino acids (BCAA) have been reported to be affected by microbiota. The association of plasma TMAO with CV mortality in Type 2 Diabetes (T2D) and its determinants are still incompletely described. We evaluated the association between plasma BCAA and TMAO, and the association of TMAO with CV mortality in T2D individuals. We used data of 595 participants (mean age 69.5 years) from the Zwolle Outpatient Diabetes project Integrating Available Care (ZODIAC) cohort were analyzed. Plasma TMAO and BCAA were measured with nuclear magnetic resonance spectroscopy. CV mortality risk was estimated using multivariable-adjusted Cox regression models. Cross-sectionally, TMAO was independently associated with BCAA standardized (Std) β = 0.18 (95% Confidence Interval (CI) 0.09; 0.27), p <0.001. During a median follow-up of 10 years, 113 CV deaths were recorded. In Cox regression analyses, adjusted for multiple clinical and laboratory variables including BCAA, TMAO was independently associated with CV mortality: adjusted hazard ratio (_adjHR) 1.93 (95% CI 1.11; 3.34), p = 0.02 (for the highest vs. the lowest tertile of the TMAO distribution). The same was true for analyses with TMAO as continuous variable: _adjHR 1.32 (95% CI 1.07; 1.63), p = 0.01 (per 1 SD increase). In contrast, BCAAs were not associated with increased CV mortality. In conclusion, higher plasma TMAO but not BCAA concentrations are associated with an increased risk of CV mortality in individuals with T2D, independent of clinical and biochemical risk markers.

Comprehensive lipid and metabolite profiling in healthy adults with low and high consumption of fatty fish: a cross-sectional study

Fish consumption is associated with reduced risk of CVD, which may be partly mediated by alterations in plasma lipids, such as HDL-cholesterol. However, comprehensive analyses of associations between fatty fish consumption and lipoprotein subclass profile are limited and show inconsistent results. Therefore, the aim of the present exploratory study was to investigate the association between fatty fish consumption and lipoprotein subclass particle concentrations and composition, with an emphasis on HDL. We performed a comprehensive plasma metabolite profiling in 517 healthy adults, using a targeted high-throughput NMR spectroscopy platform. The participants were divided into tertiles based on consumption of fatty fish, reported through a validated FFQ. We compared the concentration of metabolites between the participants in the lowest and highest tertiles of fatty fish consumption. We show that high consumers of fatty fish (>223 g/week, median intake 294 g/week) had higher particle concentrations and content of total lipids, free cholesterol and phospholipids in large and extra-large HDL particles and higher content of total cholesterol, cholesteryl esters and TAG in large HDL particles than low consumers (<107 g/week, median intake 58 g/week). Using fatty fish consumption as a continuous variable, we found that fatty fish consumption was associated with lower levels of the inflammation marker glycoprotein acetyls. In conclusion, high consumers of fatty fish seem to have a more favourable HDL-cholesterol-related lipoprotein profile and anti-inflammatory phenotype than low consumers of fatty fish. Thus, these data support the current Norwegian dietary recommendations for fish consumption regarding CVD risk.

Physiological Fitness and the Pathophysiology of Chronic Lymphocytic Leukemia (CLL)

Chronic lymphocytic leukemia (CLL) is associated with physical dysfunction and low overall fitness that predicts poor survival following the commencement of treatment. However, it remains unknown whether higher fitness provides antioncogenic effects. We identified ten fit (CLL-FIT) and ten less fit (CLL-UNFIT) treatment-naïve CLL patients from 144 patients who completed a set of physical fitness and performance tests. Patient plasma was used to determine its effects on an in vitro 5-day growth/viability of three B-cell cell lines (OSU-CLL, Daudi, and Farage). Plasma exosomal miRNA profiles, circulating lipids, lipoproteins, inflammation levels, and immune cell phenotypes were also assessed. CLL-FIT was associated with fewer viable OSU-CLL cells at Day 1 (p = 0.003), Day 4 (p = 0.001), and Day 5 (p = 0.009). No differences between the groups were observed for Daudi and Farage cells. Of 455 distinct exosomal miRNAs identified, 32 miRNAs were significantly different between the groups. Of these, 14 miRNAs had ≤-1 or ≥1 log2 fold differences. CLL-FIT patients had five exosomal miRNAs with lower expression and nine miRNAs with higher expression. CLL-FIT patients had higher HDL cholesterol, lower inflammation, and lower levels of triglyceride components (all p < 0.05). CLL-FIT patients had lower frequencies of low-differentiated NKG2+/CD158a/b^neg (p = 0.015 and p = 0.014) and higher frequencies of NKG2A^neg/CD158b+ mature NK cells (p = 0.047). The absolute number of lymphocytes, including CD19+/CD5+ CLL-cells, was similar between the groups (p = 0.359). Higher physical fitness in CLL patients is associated with altered CLL-like cell line growth in vitro and with altered circulating and cellular factors indicative of better immune functions and tumor control.

Fasting status and metabolic health in relation to plasma branched chain amino acid concentrations in women

BACKGROUND

Circulating branched chain amino acids (BCAA) are associated with cardiometabolic risk, although the mechanisms leading to their accumulation remain uncertain. Examining the relationship between fasting status, metabolic syndrome, and type 2 diabetes (T2D) with circulating BCAA levels may provide insights into their metabolic handling.

METHODS

We conducted cross-sectional analyses among 25,740 Women's Health Study participants (mean age 55 years).

RESULTS

In multivariable linear regression models, fasting was associated with lower plasma BCAAs vs. non-fasting in women without metabolic syndrome or T2D (% mean difference = -5.1%; 95% CI = -5.8, -4.5) and among women with metabolic syndrome only (-3.7%; -4.9, -2.6), p_interaction = 0.002. However, there was no difference in BCAAs by fasting status among women with T2D (0.4%; -3.7, 4.7).

CONCLUSIONS

We observed higher BCAAs with worsening metabolic health status. Fasting is modestly associated with lower plasma BCAAs, except among women with T2D. These findings support hypotheses that impaired BCAA catabolism may be a feature of T2D pathophysiology.

High-throughput nuclear magnetic resonance measurement of citrate in serum and plasma in the clinical laboratory

Objectives

Despite reports highlighting citrate association with different diseases, serum citrate is scarcely used for diagnosis. Existing methods to quantify citrate are limited by their complexity and practicality of implementation. A simple and rapid NMR-based method to measure circulating citrate is described here, and its analytical performance evaluated.

Design

and Methods: Citrate was quantified from NMR spectra using a non-negative linear least squares deconvolution algorithm. The analytical characteristics of the assay were evaluated using CLSI guidelines. To determine if the assay has adequate sensitivity to measure clinically relevant concentrations of citrate, the assay was used to quantify citrate in apparently healthy adults (n ​= ​553), and in the general population (n ​= ​133,576).

Results

The LOQ for the assay was determined to be 1.48 ​mg/dL. Linearity was demonstrated over a wide range of concentrations (1.40–4.46 ​mg/dL). Coefficients of variation (%CV) for intra- and inter-assay precision ranged from 5.8–9.3 and 5.2–9.6%, respectively. Substances tested did not elicit interference with assay results. Specimen type comparison revealed <1% bias between serum and plasma samples, except for heparin plasma (3% bias). Stability was demonstrated up to 8 days at room temperature and longer at lower temperatures. In a cohort of apparently healthy adults, the reference interval was <1.48–2.97 ​mg/dL. Slightly higher values were observed in the general population.

Conclusions

The newly developed NMR-based assay exhibits analytical characteristics that allow the accurate quantification of clinically relevant citrate concentrations. The assay provides a simple and fast means to analyze samples for research and clinical studies.

Effects of Amount, Intensity, and Mode of Exercise Training on Insulin Resistance and Type 2 Diabetes Risk in the STRRIDE Randomized Trials

Background

Lipoprotein Insulin Resistance Index (LP-IR) and Diabetes Risk Index are novel spectroscopic multimarkers of insulin resistance and type 2 diabetes risk. As the Studies of a Targeted Risk Reduction Intervention through Defined Exercise (STRRIDE) randomized trials have previously demonstrated the ability of exercise training to improve traditional markers of insulin action, the aim of this study was to examine the effects of exercise amount, intensity, and mode on LP-IR and the Diabetes Risk Index.

Methods

A total of 503 adults with dyslipidemia [STRRIDE I (n = 194), STRRIDE AT/RT (n = 139)] or prediabetes [STRRIDE-PD (n = 170)] were randomized to control or one of 10 exercise interventions, ranging from doses of 8–23 kcal/kg/week; intensities of 50–75% V̇O_2peak; and durations of 6–8 months. Two groups included resistance training and one included dietary intervention (7% weight loss goal). Fasting plasma samples were obtained at baseline and 16–24 h after the final exercise bout. LP-IR, the Diabetes Risk Index, and concentrations of the branched chain amino acids valine and leucine were determined using nuclear magnetic resonance spectroscopy. LP-IR and the Diabetes Risk Index scores range from 0–100 and 1–100, respectively (greater scores indicate greater risk). Paired t-tests determined significance within groups (p < 0.05).

Results

After training, six exercise groups significantly improved LP-IR (ranging from −4.4 ± 8.2 to −12.4 ± 14.1), and four exercise groups significantly improved the Diabetes Risk Index (ranging from −2.8 ± 8.2 to −8.3 ± 10.4). The most beneficial interventions for both LP-IR and the Diabetes Risk Index were low amount/moderate intensity aerobic, aerobic plus resistance, and aerobic plus diet.

Summary

Multiple exercise interventions improved LP-IR and the Diabetes Risk Index. In those with dyslipidemia, adding resistance to aerobic training elicited a synergistic effect on insulin resistance and type 2 diabetes risk. In individuals with prediabetes, combining a dietary intervention and weight loss with aerobic training resulted in the most robust type 2 diabetes risk improvement.

The extended lipid panel assay: a clinically-deployed high-throughput nuclear magnetic resonance method for the simultaneous measurement of lipids and Apolipoprotein B

Background

Standard lipid panel assays employing chemical/enzymatic methods measure total cholesterol (TC), triglycerides (TG), and high-density lipoprotein cholesterol (HDL-C), from which are calculated estimates of low-density lipoprotein cholesterol (LDL-C). These lipid measures are used universally to guide management of atherosclerotic cardiovascular disease risk. Apolipoprotein B (apoB) is generally acknowledged to be superior to LDL-C for lipid-lowering therapeutic decision-making, but apoB immunoassays are performed relatively infrequently due to the added analytic cost. The aim of this study was to develop and validate the performance of a rapid, high-throughput, reagent-less assay producing an “Extended Lipid Panel” (ELP) that includes apoB, using the Vantera® nuclear magnetic resonance (NMR) analyzer platform already deployed clinically for lipoprotein particle and other testing.

Methods

Partial least squares regression models, using as input a defined region of proton NMR spectra of plasma or serum, were created to simultaneously quantify TC, TG, HDL-C, and apoB. Large training sets (n > ~ 1000) of patient sera analyzed independently for lipids and apoB by chemical methods were employed to ensure prediction models reflect the wide lipid compositional diversity of the population. The analytical performance of the NMR ELP assay was comprehensively evaluated.

Results

Excellent agreement was demonstrated between chemically-measured and ELP assay values of TC, TG, HDL-C and apoB with correlation coefficients ranging from 0.980 to 0.997. Within-run precision studies measured using low, medium, and high level serum pools gave coefficients of variation for the 4 analytes ranging from 1.0 to 3.8% for the low, 1.0 to 1.7% for the medium, and 0.9 to 1.3% for the high pools. Corresponding values for within-lab precision over 20 days were 1.4 to 3.6%, 1.2 to 2.3%, and 1.0 to 1.9%, respectively. Independent testing at three sites over 5 days produced highly consistent assay results. No major interference was observed from 38 endogenous or exogenous substances tested.

Conclusions

Extensive assay performance evaluations validate that the NMR ELP assay is efficient, robust, and substantially equivalent to standard chemistry assays for the clinical measurement of lipids and apoB. Routine reporting of apoB alongside standard lipid measures could facilitate more widespread utilization of apoB for clinical decision-making.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12944-020-01424-2.

Metabolite biomarkers of type 2 diabetes mellitus and pre-diabetes: a systematic review and meta-analysis

BACKGROUND

We aimed to explore metabolite biomarkers that could be used to identify pre-diabetes and type 2 diabetes mellitus (T2DM) using systematic review and meta-analysis.

METHODS

Four databases, the Cochrane Library, EMBASE, PubMed and Scopus were selected. A random effect model and a fixed effect model were applied to the results of forest plot analyses to determine the standardized mean difference (SMD) and 95% confidence interval (95% CI) for each metabolite. The SMD for every metabolite was then converted into an odds ratio to create an metabolite biomarker profile.

RESULTS

Twenty-four independent studies reported data from 14,131 healthy individuals and 3499 patients with T2DM, and 14 included studies reported 4844 healthy controls and a total of 2139 pre-diabetes patients. In the serum and plasma of patients with T2DM, compared with the healthy participants, the concentrations of valine, leucine, isoleucine, proline, tyrosine, lysine and glutamate were higher and that of glycine was lower. The concentrations of isoleucine, alanine, proline, glutamate, palmitic acid, 2-aminoadipic acid and lysine were higher and those of glycine, serine, and citrulline were lower in prediabetic patients. Metabolite biomarkers of T2DM and pre-diabetes revealed that the levels of alanine, glutamate and palmitic acid (C16:0) were significantly different in T2DM and pre-diabetes.

CONCLUSIONS

Quantified multiple metabolite biomarkers may reflect the different status of pre-diabetes and T2DM, and could provide an important reference for clinical diagnosis and treatment of pre-diabetes and T2DM.

Citrus flavonoids and the intestinal barrier: Interactions and effects

The intestinal barrier plays a central role in sustaining gut homeostasis and, when dysfunctional, may contribute to diseases. Dietary flavonoids derived from Citrus genus represent one of the main naturally occurring phytochemicals with multiple potential benefits for the intestinal barrier function. In the intestine, citrus flavonoids (CFs) undergo ingestion from the lumen, biotransformation in the epithelial cells and/or crosstalk with luminal microbiota to afford various metabolites that may in turn exert protective actions on gut barrier along with their parental compounds. Specifically, the health-promoting properties of CFs and their metabolic bioactives for the intestinal barrier include their capacity to (a) modulate barrier permeability; (b) protect mucus layer; (c) regulate intestinal immune system; (d) fight against oxidative stress; and (e) positively shape microbiome and metabolome. Notably, local effects of CFs can also generate systemic benefits, for instance, improvement of gut microbial dysbiosis helpful to orchestrate gut homeostasis and leading to alleviation of systemic dysmetabolism. Given the important role of the intestinal barrier in overall health, further understanding of underlying action mechanisms and ultimate health effects of CFs as well as their metabolites on the intestine is of great significance to future application of citrus plants and their bioactives as dietary supplements and/or functional ingredients in medical foods.

Association of the Mediterranean Diet With Onset of Diabetes in the Women's Health Study

IMPORTANCE

Higher Mediterranean diet (MED) intake has been associated with reduced risk of type 2 diabetes, but underlying biological mechanisms are unclear.

OBJECTIVE

To characterize the relative contribution of conventional and novel biomarkers in MED-associated type 2 diabetes risk reduction in a US population.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study was conducted among 25 317 apparently healthy women. The participants with missing information regarding all traditional and novel metabolic biomarkers or those with baseline diabetes were excluded. Participants were invited for baseline assessment between September 1992 and May 1995. Data were collected from November 1992 to December 2017 and analyzed from December 2018 to December 2019.

EXPOSURES

MED intake score (range, 0 to 9) was computed from self-reported dietary intake, representing adherence to Mediterranean diet intake.

MAIN OUTCOMES AND MEASURES

Incident cases of type 2 diabetes, identified through annual questionnaires; reported cases were confirmed by either telephone interview or supplemental questionnaire. Proportion of reduced risk of type 2 diabetes explained by clinical risk factors and a panel of 40 biomarkers that represent different physiological pathways was estimated.

RESULTS

The mean (SD) age of the 25 317 female participants was 52.9 (9.9) years, and they were followed up for a mean (SD) of 19.8 (5.8) years. Higher baseline MED intake (score ≥6 vs ≤3) was associated with as much as a 30% lower type 2 diabetes risk (age-adjusted and energy-adjusted hazard ratio, 0.70; 95% CI, 0.62-0.79; when regression models were additionally adjusted with body mass index [BMI]: hazard ratio, 0.85; 95% CI, 0.76-0.96). Biomarkers of insulin resistance made the largest contribution to lower risk (accounting for 65.5% of the MED-type 2 diabetes association), followed by BMI (55.5%), high-density lipoprotein measures (53.0%), and inflammation (52.5%), with lesser contributions from branched-chain amino acids (34.5%), very low-density lipoprotein measures (32.0%), low-density lipoprotein measures (31.0%), blood pressure (29.0%), and apolipoproteins (23.5%), and minimal contribution (≤2%) from hemoglobin A1c. In post hoc subgroup analyses, the inverse association of MED diet with type 2 diabetes was seen only among women who had BMI of at least 25 at baseline but not those who had BMI of less than 25 (eg, women with BMI <25, age- and energy-adjusted HR for MED score ≥6 vs ≤3, 1.01; 95% CI, 0.77-1.33; P for trend = .92; women with BMI ≥25: HR, 0.76; 95% CI, 0.67-0.87; P for trend < .001).

CONCLUSIONS AND RELEVANCE

In this cohort study, higher MED intake scores were associated with a 30% relative risk reduction in type 2 diabetes during a 20-year period, which could be explained in large part by biomarkers of insulin resistance, BMI, lipoprotein metabolism, and inflammation.

Circulating branched-chain amino acids and long-term risk of obesity-related cancers in women

Obesity is a risk factor for > 13 cancer sites, although it is unknown whether there is a common mechanism across sites. Evidence suggests a role for impaired branched-chain amino acid (BCAAs; isoleucine, leucine, valine) metabolism in obesity, insulin resistance, and immunity; thus, we hypothesized circulating BCAAs may be associated with incident obesity-related cancers. We analyzed participants in the prospective Women’s Health Study without a history of cancer at baseline blood collection (N = 26,711, mean age = 54.6 years [SD = 7.1]). BCAAs were quantified via NMR spectroscopy, log-transformed, and standardized. We used Cox proportional regression models adjusted for age, race, smoking, diet, alcohol, physical activity, menopausal hormone use, Body Mass Index (BMI), diabetes, and other risk factors. The endpoint was a composite of obesity-related cancers, defined per the International Agency for Research on Cancer 2016 report, over a median 24 years follow-up. Baseline BMI ≥ 30 kg/m² compared with BMI 18.5–25.0 kg/m² was associated with 23% greater risk of obesity-related cancers (n = 2751 events; multivariable HR 1.23, 95% CI 1.11–1.37). However, BCAAs were not associated with obesity-related cancers (multivariable HR per SD = 1.01 [0.97–1.05]). Results for individual BCAA metabolites suggested a modest association for leucine with obesity-related cancers (1.04 [1.00–1.08]), and no association for isoleucine or valine (0.99 [0.95–1.03] and 1.00 [0.96–1.04], respectively). Exploratory analyses of BCAAs with individual sites included positive associations between leucine and postmenopausal breast cancer, and isoleucine with pancreatic cancer. Total circulating BCAAs were unrelated to obesity-related cancer incidence although an association was observed for leucine with incident obesity-related cancer.

A Newly Developed Diabetes Risk Index, Based on Lipoprotein Subfractions and Branched Chain Amino Acids, is Associated with Incident Type 2 Diabetes Mellitus in the PREVEND Cohort

Objective: Evaluate the ability of a newly developed diabetes risk score, the Diabetes Risk Index (DRI), to predict incident type 2 diabetes mellitus (T2D) in a large adult population. Methods: The DRI was developed by combining the Lipoprotein Insulin Resistance Index (LP-IR), calculated from 6 lipoprotein subspecies and size parameters, and the branched chain amino acids, valine and leucine, all of which have been shown previously to be associated with future T2D. DRI scores were calculated in a total of 6134 nondiabetic men and women in the Prevention of Renal and Vascular End-Stage Disease (PREVEND) Study. Cox proportional hazards regression was used to evaluate the association of DRI scores with incident T2D. Results: During a median follow-up of 8.5 years, 306 new T2D cases were ascertained. In analyses adjusted for age and sex, there was a significant association between DRI scores and incident T2D with the hazard ratio (HR) for the highest versus lowest quartile being 12.07 (95% confidence interval: 6.97–20.89, p < 0.001). After additional adjustment for body mass index (BMI), family history of T2D, alcohol consumption, diastolic blood pressure, total cholesterol, triglycerides, HDL cholesterol and HOMA-IR, the HR was attenuated but remained significant (HR 3.20 (1.73–5.95), p = 0.001). Similar results were obtained when DRI was analyzed as HR per 1 SD increase (HR 1.37 (1.14–1.65), p < 0.001). The Kaplan–Meier plot demonstrated that patients in the highest quartile of DRI scores presented at higher risk (p-value for log-rank test <0.001). Conclusions: Higher DRI scores are associated with an increased risk of T2D. The association is independent of clinical risk factors for T2D including HOMA-IR, BMI and conventional lipids.

Plasma branched chain amino acids are lower in short-term profound hypothyroidism and increase in response to thyroid hormone supplementation

Branched chain amino acids (BCAA) are implicated in the pathogenesis of cardiometabolic diseases conceivably by affecting insulin resistance and mitochondrial dysfunction. Circulating BCAA levels may predict (subclinical) atherosclerosis, diabetes and hypertension development but the factors involved in BCAA regulation are incompletely understood. Given the key role of thyroid hormones on many metabolic processes including protein metabolism, we aimed to determine effects of thyroid dysfunction on circulating BCAA. Effects of short-term profound hypothyroidism on plasma BCAA were determined in 17 patients who had undergone total thyroidectomy for differentiated thyroid carcinoma. Patients were studied during hypothyroidism, i.e. after thyroidectomy, and after thyroid hormone supplementation. Plasma BCAA (sum of valine, leucine and isoleucine) and alanine were measured by nuclear magnetic resonance spectroscopy. During hypothyroidism (median thyroid-stimulating hormone 81 (IQR 67-120.5) mU/L), plasma BCAA were lower (255 (IQR 222-289) µmol/L) compared to a euthyroid reference population (n = 5579; 377 µmol/L (2.5th to 97.5th percentile 258-548), p < 0.001). After 20 weeks of thyroid hormone supplementation (thyroid-stimulating hormone 0.03 (IQR 0.01-0.14 mU/L) plasma BCAA had increased (328 (IQR 272-392) µmol/L, p = .001), but plasma alanine concentrations were unaltered (p = .50). Changes in body weight in response to thyroid hormone supplementation were correlated with changes in plasma BCAA (r = 0.721 p = .001, but not with changes in cholesterol or glucose (p > .80). In conclusion, plasma BCAA concentrations are lower during short-term profound hypothyroidism in humans, and increase in response to thyroid hormone supplementation. Changes in BCAA and in body weight after reversal of the hypothyroid state appear to be interrelated.

A Translational In Vivo and In Vitro Metabolomic Study Reveals Altered Metabolic Pathways in Red Blood Cells of Type 2 Diabetes

Clinical parameters used in type 2 diabetes mellitus (T2D) diagnosis and monitoring such as glycosylated haemoglobin (HbA1c) are often unable to capture important information related to diabetic control and chronic complications. In order to search for additional biomarkers, we performed a pilot study comparing T2D patients with healthy controls matched by age, gender, and weight. By using ¹H-nuclear magnetic resonance (NMR) based metabolomics profiling of red blood cells (RBCs), we found that the metabolic signature of RBCs in T2D subjects differed significantly from non-diabetic controls. Affected metabolites included glutathione, 2,3-bisphophoglycerate, inosinic acid, lactate, 6-phosphogluconate, creatine and adenosine triphosphate (ATP) and several amino acids such as leucine, glycine, alanine, lysine, aspartate, phenylalanine and tyrosine. These results were validated by an independent cohort of T2D and control patients. An analysis of the pathways in which these metabolites were involved showed that energetic and redox metabolism in RBCs were altered in T2D, as well as metabolites transported by RBCs. Taken together, our results revealed that the metabolic profile of RBCs can discriminate healthy controls from T2D patients. Further research is needed to determine whether metabolic fingerprint in RBC could be useful to complement the information obtained from HbA1c and glycemic variability as well as its potential role in the diabetes management.